A Schottky-contact triangular-barrier optoelectronic switch (STOS)

A Schottky-contact triangular-barrier optoelectronic switch (STOS), grown by molecular beam epitaxy, has been fabricated. The triangular barrier, formed by inserting an InGaAs delta-doped (/spl delta/-doped) quantum well into an n/sup -/-GaAs layer, provides a potential well for hole accumulation. Due to the hole accumulation in the /spl delta/-doped well and the sequential avalanche multiplications in the reverse-biased p-n and metal-semiconductor junctions, a double S-shaped negative-differential-resistance phenomenon is observed in the current-voltage (I-V) characteristics. The STOS shows a flexible optical function related to the triangular barrier height controllable by incident light. The multistate is switchable by both optical and electrical inputs.     

An optoelectronic switch based on a triangular-barrier structure

A GaAs-InGaP triangular-barrier optoelectronic switch, grown by metalorganic chemical vapor deposition (MOCVD), is reported in the paper. Owing to the avalanche multiplication and hole confinement in the device operation, S-shaped negative-differential-resistance (NDR) performances are observed in the current-voltage (I-V) characteristics under both normal and reverse operation modes. The device also showed a flexible optical function related to the potential barrier height controllable by incident light. The dependency of the carrier transport mechanism on illumination, as well as the I-V characteristics at different temperatures, are investigated     

Different types of optoelectronic bistabilities inresonant-tunnelling triangular-barrier optoelectronic switch (R-TOPS)

Novel optoelectronic bistabilities in a resonant-tunnelling triangular-barrier optoelectronic switch (R-TOPS) are reported. Optically controlled S-shaped and N-shaped NDRs were observed simultaneously in a single device. Different types of optoelectronic bistabilities originated from S-shaped and N-shaped NDRs were obtained by changing the input light power     

A simple 8×8 optoelectronic crossbar switch

The authors demonstrate the operation of an 8×8 optoelectronic crossbar switch consisting of integrated arrays of eight 1×8 GaAs metal-semiconductor-metal (MSM photodiodes connected in a current summing network to the input of Si bipolar transimpedance amplifiers. The MSM devices are also connected to TTL transistor-transistor logic) driven CMOS analog multiplexers which, in the `off' state, switch the detectors into an open-circuit mode. This particular combination of detectors and switching network gives a very high interchannel isolation, reduced circuit complexity, and low input noise. Data rates of 200 Mbit's and switch reconfiguration times of -100 ns are achieved. System noise is calculated and measured, and the advantages of using fully integrated GaAs crossbar switch arrays are quantitatively discussed     

Si/SiGe digital optoelectronic switch

The physical parameters and functional characteristics of a Si/SiGe digital optoelectronic switch are reported. The device is found to have bistable electrical states: a high-impedance (40 kΩ) OFF state connected to a low-impedance (100 Ω) ON state by a regime of negative differential resistance. The switching voltage and holding voltage are measured to be 2.6 and 1.3 V, respectively, and the switching current and holding current are measured to be 500 μA and 1 mA, respectively. These DC characteristics are found to be similar to those measured in double heterostructure optoelectronic switching devices manifested in the AlGaAs/GaAs materials system. The DC characteristics of this Si/SiGe digital optoelectronic switch are also found to be sensitive to optical input and temperature     

InP/InGaAsP double-heterostructure optoelectronic switch

The double-heterostructure optoelectronic switch (DOES), fabricated in the InP/InGaAsP material system, is demonstrated. The functional characteristics and operational parameters exhibit a lower switching voltage (≈1.8 V) and a higher on-state holding current (≈20 mA) than found in either the Si/SiGe- or GaAs/AlGaAs-based DOES of comparable structures and doping levels. In the on-state, optical emission is observed in a manner analogous to a light emitting diode. However, enhanced optical emission is observed when the device is biased in the regime of negative differential resistance     

A thyristor-based photoreceiver based on the dual-channel double-heterostructure optoelectronic switch

A new approach to photoreceiver design is described based on the functionality of an optoelectronic thyristor. The receiver eliminates the transimpedance amplifier and the decision circuit by utilizing the internal gain of the thyristor and its nonlinear thresholding property. The sensitivity is determined by the shot noise on the input signal to be 360 photons per bit at a bit-error rate of 10/sup -9/. The speed of the photoreceiver is determined by the switching times of the thyristor. An output voltage signal from 0 to 1.5 V is obtained with switch on and off times of 12.5 ps and input photocurrent densities of 10/sup 4/ A/cm/sup 2/. The switch off time is equally as fast as the switch on due to the absence of stored charge in the modulation doped structure. The key to the high speed is the utilization of the third and fourth terminal contacts to the thyristor and the integration of the biasing transistors, which control the switching currents. An input optical signal of 0.5 mW will achieve this bandwidth in a device size of 0.2 /spl mu/m/spl times/12.5 /spl mu/m.     

Theoretical model for a microsctip optoelectronic switch

A theoretical model is given to represent the active part of either an optoelectronic switch, similar to those described by Auston el al., or an optoelectronic gate such as the one we developed. These devices consist mainly of a microstrip line, with a characteristic impedance of 50 ?, which is deposited on a high-resistivity semiconductor. The centre strip has a break, creating a gap which can be illuminated by an optical laser pulse. The latter generates an electron-hole plasma of high density at the surface of the semiconductor, allowing the transmission of a signal across the gap.     

8×8 optoelectronic crossbar switch

An optoelectronic crossbar switch has been fabricated and tested at 100-175 Mbit/s. The optoelectronic switching is achieved using bias switched detectors     

A new AlGaAs/GaAs/InAlGaP npn bulk-barrier optoelectronic switch

Two-terminal switching performance is observed in a new AlGaAs/GaAs/InAlGaP optoelectronic device. The device shows that the switching action takes place from a low current state to a high current state through a region of negative differential resistance (NDR). The transition from either state to the other may be induced by an appropriate optical or electrical input. It is seen that the effect of illumination increases the switching voltage V/sub S/ and decreases the switching current I/sub S/, which is quite different from other results reported. In addition, it possesses obvious NDR even up to 160/spl deg/C. This high-temperature performance provides the studied device with potential high-temperature applications.     

High-speed CMOS switch designs for free-space optoelectronic MIN's

We present the theory, experimental results, and analytical modeling of high-speed complementary metal-oxide-semiconductor (CMOS) switches, with a two-dimensional (2-D) layout, suitable for the implementation of packet-switched free-space optoelectronic multistage interconnection networks (MIN's). These switches are fully connected, bidirectional, and scaleable. The design is based on the implementation of a half-switch, which is a two-to-one multiplexer, using a 2-D layout. It introduces a novel self-routing concept, with contention detection and packet drop-and-resend capabilities. It uses three-valued logic, with 2.5 V being the third value for a 5 V power supply. Simulations show that for a 0.8-μm CMOS technology the switches can operate at speeds up to 250 Mb/s. Scaled-down versions of the switches have been successfully implemented in 2.0 μm CMOS. The analytical modeling of these switches show that large scale free-space optoelectronic MIN's using this concept could offer close to Terabit/sec throughput capabilities for very reasonable power and area figures. For example, a 4096 channel system could offer 256 Gb/s aggregate throughput for a total silicon area of about 18 cm² and a total power consumption (optics plus electronics) of about 90 W     

Electrical switching speed of the double-heterostructure optoelectronic switch

The electrical switching speed of a new double-heterostructure optoelectronic switch (designated DOES) is measured in a relaxation oscillator circuit. A minimum value of capacitance was required to obtain oscillations. The turn-on speed was measured to be 100 ps. The turn-off speed was limited to the RC pull-up time.     

New reflection-type optoelectronic microwave switch for CW applications

The operation of a new type of optoelectronic switch is described. Using the principle of an optically controlled reflection coefficient, the capacitive effects of conventional gap-discontinuity devices are eliminated and the insertion loss can be made extremely low. This switch offers the possibility in the millimetre wave range.<>     

Integrated optical/optoelectronic switch for parallel opticalinterconnects

A monolithic optical/optoelectronic switch for a reconfigurable, parallel optical interconnect is described. By integrating a vertical-cavity surface-emitting laser with a three-terminal GaAs-AlGaAs heterojunction phototransistor, the functions of an optical transceiver and an optical space switch are combined. Switching experiments demonstrate optical/optoelectronic switching and data conversion at 200 Mbit/s     

Electrical and optical properties of the three-terminaldouble-heterostructure optoelectronic switch

A theory is developed for the three-terminal version of the double-heterojunction optoelectronic switch (DOES), in which the third terminal, the injector, makes ohmic contact to the active layer of the device. The injector permits the biasing of the active-layer-substrate junction, the effect of which is to reduce the threshold voltage at which switching from the electrical and optical OFF-state to the ON-state occurs. Reverse baising the junction initiates switching from the ON- to the OFF-state. The current and optical output as a function of voltage with the injector current as a parametric variable are plotted in terms of the physical and geometrical properties of the device     

Fast photoconductive optoelectronic broadband switch with low control voltage

Optoelectronic switching with a gallium arsenide field-effect transistor used as a photoconductive detector is demonstrated. On-state to off-state isolation ratios of 65 dB from 500 kHz to 1.3 GHz, and switching times less than 10 ns, are observed. Gating voltage is of the order of 3?10 V.     

Characteristics of a photoconductive detector as an optoelectronic switch

Measurements of the wavelength, signal frequency, and position sensitivities of GaAs field effect transistors used as photoconductive detectors are presented. Switching of the optical sensitivity by means of both the drain and gate voltages are demonstrated. The former method can provide the basis for employing such photoconductive detectors as optoelectronic wide-band switches. The observed properties of the field effect transistor (FET) devices studied shows that the design of photoconductive optoelectronic switches will involve compromises between sensitivity and isolation in choosing the operating wavelength, and among frequency response, power consumption, and physical size in choosing the physical layout of the device.     

New double heterostructure optoelectronic triangular barrier switch (OETBS)

A new high-speed, high-power optoelectronic device, with a double heterostructure, is proposed and demonstrated. The device has bistable electrical characteristics where light emission occurs in the on-state. The high optical power output was measured to be 209?W at 100 mA. The transient electrical and optical rise times have been measured to be 500 ps and 1 ns, respectively.     

Design and performance of an optoelectronic matrix switch usingSi-p-i-n photodiodes

Switching speed, isolation, optical-source requirements, and attainable matrix dimensions of an optoelectronic matrix switch using Si p-i-n photodiodes are discussed. By charging the internal capacitance of the diode with a photocurrent, forward bias voltages are attained that establish off-states. The novel features of the matrix switch are that the switch elements have high output impedance at off-states, and no electrical power is required to establish the off-states. This leads to advantages in fabricating large-dimension matrix switches     

Modeling of optoelectronic switch with PIN photodiode and GaAsMESFET transmission gate

A broadband and high-isolation optoelectronic switch, which consists of a PIN photodiode and a GaAs MESFET in common gate configuration as a transmission gate, was theoretically and experimentally investigated. An analytical model has been developed to calculate the isolation level of the switch. The influences on the isolation level from different device parameters were studied. Experimental results obtained using commercial components validate the operation of the proposed switch. Measured isolation of 70 dB at 300 kHz and 55 dB up to 1.0 GHz were achieved. Good agreement has been obtained between the measured and calculated results and therefore the model developed has been validated